Effects of key process parameters of Cansolv tail gas treatment unit on up-to-standard emission and control measures

Objective To determine the effect of key process parameters of Cansolv tail gas treatment unit on the tail gas emission, and achieve SO₂ in tail gas up-to-standard emission.

Method By analyzing the factors affecting SO₂ mass concentration in tail gas, it is concluded that the SO₂ mass concentration in tail gas is mainly influenced by the operating factors such as total sulfur content in tail gas entering the Cansolv device, thermal stabilization salt content in organic amine, lean liquid pH value and DS solution circulation.

Results The following measures have been taken to optimize the operation of the device: (1) The stable operation of the desulfurization device can be achieved by reducing the component and flow fluctuation of acid gas and flash gas; (2) The air distribution must be strictly controlled according to the volume ratio of H₂S to SO₂ is 2∶1; (3) The volume fraction of impurities must be controlled, such as SO₃ acid mist in the process gas entering the SO₂ absorption tower less than 10×10^-6; (4) The operation of the amine purification device was optimized; (5) The molar ratio of thermally stable salt to organic amine in the DS solution system of 1.1~1.3 must be controlled strictlly; (6) The mass fraction and poverty of poor DS organic amine must be controlled.

Conclusions After taking above measures, the mass concentration of SO₂ in the exhaust gas was not greater than 400 mg/m³, which could meet the emission limit requirement in GB 39728-2020 Emission Standard of Air Pollutants for Onshore Oil and Gas Exploitation and Production Industry aiming at the total size of sulfur recovery unit greater than or equal to 200 t/d.